ABSTRACT: Open peritoneal drainage is not a common procedure, but may be used in severe cases of septic peritonitis as an alternative to closing the abdomen and placing active suction drains. The veterinary nurse's role becomes important as these patients require intensive monitoring and nursing. This article aims to explain the procedure, and the role of the nurse to make sure the patient has the best outcome possible.

The decision to use open peritoneal drainage for the treatment of septic peritonitis is the veterinary surgeons. However, these cases require very intensive nursing and so will often fall into the remit of the veterinary nurse.

The nurse must be fully aware of the treatment regimen that these patients require, the complications that may arise and the way they can be treated or prevented. This article aims to explain the procedure and the role of the nurse to make sure the patient has the best outcome possible.

Open peritoneal drainage essentially treats the peritoneal cavity as a giant abscess and as such, is left open in order to drain. It also provides easy access to lavage the cavity and monitor the exudate being produced.

Indications

Open peritoneal drainage was initially used to treat human patients with gross peritoneal contamination to try and reduce the extremely high morbidity rates. This technique has been transferred to veterinary medicine to treat patients with septic peritonitis which is commonly caused by gastro-intestinal perforation with food contents leakage, abdominal trauma or necrotising pancreatitis.

Typically, presentation occurs around three to five days after an initial laparotomy for gastro-intestinal surgery. During the healing phase there is a greater risk of anastomosis breakdown which may lead to peritonitis. It does involve fairly intensive nursing so may not be suitable in all practices, but can be of benefit in some cases.

The temperament of the patient undergoing this regimen should be considered before the decision to use this option is made. Compliance of the patient is required, especially during the bandage changes. Cats are not usually suitable candidates.

These cases are often very sick and the outcome is particularly poor, with up to 50 per cent mortality. Often this technique is used in cases where euthanasia is the only alternative option. There is little research in veterinary medicine to show that this technique provides any benefit and in human medicine there are significant complication rates with no advantage shown over closed methods. However, as our patients walk on four legs rather than two, it is thought that gravity allows it to provide more benefit.

Initial treatment

Treatment prior to surgery requires stabilisation to correct metabolic disturbances. Intravenous fluid therapy, vasopressors, inotropic therapy and analgesia may all be required before diagnostic imaging and abdominocentesis is performed. Intravenous antibiotics should be started after samples have been collected for culture and sensitivity testing, to ensure the correct antibiotic is used.

Surgery

Routine laparotomy surgery is required to treat the initial cause of the peritonitis. The cause of the contamination needs to be rectified surgically, before lavage of the abdominal cavity. Copious amounts of warmed saline are required to remove as much as possible of the contamination – often several litres and up to as many as 10 litres for a large breed dog. This should be continued until the fluid in the suction bottle is clear and all large particulate matter is removed. Open peritoneal drainage is not a substitute for this process but a continuation of the treatment.

At the end of the surgery the abdominal incision is partially closed but still allows continuous drainage of the cavity. Sutures, usually monofilament, are placed in the caudal and cranial edges of the linea alba. This loose continuous suture prevents organ herniation but allows drainage of fluid (Figure 1).

Figure la, 1b, 1c: Loose sutures are placed in the cranial and caudal ends of the wounds to prevent abdominal organs from herniating

Figure Id: The wound before it is dressed with sterile absorbent swabs and then wrapped in multi-layers of bandage

Post-operative bandaging

Before the patient has recovered from anaesthesia the wound must be covered. Large sterile laparotomy swabs are packed into the area by the surgeon, wearing sterile gloves. This layer is then covered with a thick layer of cotton wool or cotton wool-type bandage as an absorption layer.

It is then followed by an absorbent waterproof layer to try and prevent strike-through’. Sterilised incontinence sheets or disposable nappies are often used and work well. The subsequent layers provide support and protection, in the same way as a tertiary layer in a bandage would do.

Recovery

Indwelling urinary catheters should be routinely placed, especially in male dogs, to prevent contamination of the bandage – and potentially the wound – with urine. A closed system with a collection bag should be used. This also allows the amount of urine produced to be monitored to ensure an output of 1-2 mls/kg/hour. Although other methods of measuring blood pressure should be used, using urine output as a general indicator of renal perfusion – and therefore blood pressure – is a valuable guideline.

As previously mentioned, the nursing care of these patients can be fairly intensive. It is not advisable to leave them on their own at all and so facilities that provide 24-hour nursing care are required. If these are not available, the patient may need referral to a specialist hospital.

Patients should be housed in a kennel large enough for them to move around comfortably but small enough to prevent them jumping or stretching excessively. A Buster collar may be required to prevent interference with the bandage and patients must be barrier nursed at all times (Figure 2).

Figure 2: Barrier nursing prevents contamination to and from the patient

 

Analgesia

Opioids are the analgesia of choice for these cases. Morphine or methadone should be administered regularly during the initial post-operative period. Non¬steroidal anti-inflammatory drugs should be avoided because of possible gastro intestinal implications.

Bandage changes

This treatment regimen requires the bandages to be changed regularly. Depending on the amount of fluid produced, this may need to be up to twice daily. If‘strike-through’ becomes visible, they should be changed immediately.

The patient can be at risk of nosocomial infection and there is a risk to other immuno-suppressed patients if exudate passes from this bandage to other areas of the ward
unnoticed.

Analgesics given just prior to the dressing change can also help keep the patient calm and changing of the bandages does not necessarily have to be done under general anaesthesia.

Ideally the bandage is changed with the patient in a standing position – on a table, if a small breed or on the floor, if a large breed. A sterile drape should be placed under the abdomen in case evisceration of the abdomen occurs accidentally.

If the patient is recumbent the dressing can be changed more easily with the patient lying across two tables with a gap in the middle. (Figure 3).

Figure 3: The use of two trolleys to aid dressing changes, especially in larger patients

The outer layers of bandages should be removed by a person wearing gloves to prevent contamination. Once the inner swab layers of the bandage are reached, these gloves should be replaced by sterile gloves put on in a sterile manner.

Adhesions which have formed may need to be broken down to ensure drainage continues. This is done by inserting a sterile gloved finger into the abdomen.

Dressings should be discarded into a clinical waste bag immediately to prevent contamination to the environment and potentially to other patients. However, they are often weighed first to provide a rough estimation of fluid loss and examined for the presence of obvious contamination.

Blood sample analyses

Blood samples are routinely screened. Special attention is paid to electrolytes and serum protein level imbalances. Both of these are lost in the exudate and so may need to be replaced.

Protein losses through peritoneal fluid lead to hypoalbuminaemia. Plasma transfusions or synthetic colloid solutions may be required to maintain serum albumin levels, although whole blood can be used if blood products are not able to be separated. Pitting oedema of the limbs may be present as a consequence of the hypoalbuminaemia.

Intravenous fluid therapy, with compound sodium lactate, should be continued throughout treatment. Addition of potassium chloride may be needed if the patient is, or becomes, hypokalaemic.

Monitoring

Temperature, pulse rate, its quality and strength, and respiration rate should be monitored. Direct and indirect blood pressure monitoring should be performed regularly and consistently. The patient’s general demeanour should be monitored by the nurse at all times and any sudden changes brought to the attention of the veterinary surgeon.

Nutrition

It is important to re-introduce feeding as soon as possible. This may depend on the surgery performed, although recovery of the intestinal mucosa by reintroducing food as soon as the patient is fully recovered from general anaesthesia is advised. If the patient remains recumbent or sedated during treatment or is not interested in eating it may be necessary to place a feeding tube.

Oesophagostomy or gastrotomy tubes can be placed pre-emptively at the time of the first surgery. The metabolic requirements for these patients are similar to those of a patient with severe burns. Weight loss must be monitored closely – weighing the patient on a daily basis may not give a true representation because of the bulky dressing and fluid production.

When to close the abdomen?

This decision is taken on a case-by-case basis. Treatment using open peritoneal drainage usually lasts approximately three to seven days, but the decision to close is based on a number of factors. These include a reduction in the volume and bacterial count in the fluid being produced and visible reduction in gross contamination on the dressings.

The patient is returned to theatre, with swabs kept over the wound during skin preparation. Alcohol-based products should be avoided to prevent irritation. The wound edges are debrided and the abdomen lavaged with large volumes of warmed sterile saline. Routine laparotomy closure is then performed.

Complications

There are a number of potential complications involved in these cases. Persistent fluid loss, weight loss, adhesions of the abdominal viscera to the bandage and contamination of the peritoneal cavity with cutaneous organisms are all potential complications.

Alternatives

Active suction drains can be placed in the abdominal cavity to provide drainage. This obviously has the advantage of a single-stage procedure, but the tubes may become blocked with tissue debris or omentum.

Conclusions

These cases take a great deal of nursing time and effort. There are risks and considerations to be taken into account before a decision can be made to treat a patient with an open peritoneal drainage regimen. Contamination of the local environment and other patients, hospital- acquired infections and abdominal organ herniation all need to be considered. However, because of the intensive nursing care required, the rewards when the outcome is favourable are very positive for the team. 3

Author

Alison Young RVN DipAVN [Surg]

Alison Young worked in a small animal practice in Hertfordshire where she qualified as a veterinary nurse. In 2001, she joined the Queen Mother Hospital at the RVC as a surgery nurse. In 2005, she took the Diploma in Advanced Veterinary Nursing (Surgical) and became senior, then head, theatre nurse.

To cite this article use either

DOI: 10.1111/j.2045-0648.2011.00048 x or Veterinary Nursing Journal Vol 26 pp 189-191

Veterinary Nursing Journal • Vol l26 • June 2011 •